I think some people are missing the point of interiors. They’re used for immersion, fun, and in some cases they are necessary or beneficial. It’s the physical environment in GTA that gives it a sense of life and this also applies to interiors. Some people arguing against them are suggesting they’re a waste of space, only to be entered once and never again.
Banks – On completion, it becomes increasingly hard to earn cash. Banks would offer as an alternative for obtaining relatively lucrative amounts, albeit extremely difficult to obtain.
Cluckin’Bell/Burger Shot – This one’s obvious: Replenish user’s health. I found they added a lot of character, immersion and humour to San Andreas.
Police Station/Hospital – They could be copied and pasted throughout the map. I always enjoyed wreaking havoc in the police station in previous GTAs. For added immersion, after being busted/wasted, you could be spawned in the entrance hall.
Motels – They could be located throughout the vast rural landscape, serving as save/health replenishment points. They could be deemed necessary if the quick save feature was removed, and helpful for restoring health. Also, an alternative place to take prostitutes if you’re into that sort of thing.
Safe Houses – The same as above. Not too many though, and make them useful. Condo’s with helipads, or houses with garages.
Bars – Bars offer more activities. Pool, arcade machines, bar brawls, etc. Your character could ring friends/acquaintances like in previous GTAs (although not the other way around). It would be awesome getting wasted with Trevor.
Businesses – In Vice City it actually felt like you owned your assets/properties. This was a major aspect of immersion and the feeling of building and owning an empire, and that's the primary focus of each story told in GTA. Most characters are going from rags to riches.
Shopping mall – For the fun factor. Who didn’t enjoy causing havoc in the mall in Vice City.
They're just some suggestions. It has nothing to do with being whiny kids. It seems you can't critisize the game at all without people circle-jerking and contorting your actual points to make them sound ridiculous. I see a lot of features/locations with little substance that people enjoy having in this game, inadvertently adding to the immersion/realism. It's no different with the interiors.